This test is for patients of the practice. Enter the access code your office gave you when your visit was arranged, then tap Continue.
If you don't have a code, please contact the office and we will be glad to provide one.
This is a screening test, not a diagnosis and not a prescription. Results depend on your screen and lighting, and they do not replace an in-office contrast sensitivity examination.
This screener measures contrast sensitivity — how faint a large letter you can still read. Letters are shown three at a time, bold at first, then fainter and fainter, in the tradition of the Pelli-Robson chart used in the clinic. The fainter the letters you can read, the better your contrast sensitivity.
Hold a real credit card (or any bank card) against the outline below and drag the slider until the outline is exactly the width of the card. This tells the test your screen's true size, so the letters appear at the intended size for a 40 cm viewing distance.
The letters below are shown at test size, at full contrast, exactly as they will appear:
Used only on your report, so the office can match it to your chart.
A home screen limits how precise this test can be: screen brightness, glare, and the grey steps an ordinary display can show all affect the faintest letters, and the very lowest contrasts are coarse on most screens. The printed contrast chart in the clinic remains the definitive measure. This screening gives the office a useful first picture — it is not a diagnosis and not a prescription.
Tap the letters you can read, in order, left to right.
Keep the covered eye covered, stay 40 cm (about 16 inches) from the screen, and don't change the brightness partway through — steady conditions make the result mean something.
Rest your eyes for a moment. Then cover the right eye instead, keep the left eye open, and settle back at the same 40 cm distance before you continue.
Both eyes are done. Your screening report is below.
Contrast Sensitivity Screening Report — Paddy Kalish OD, 1296 Beacon St, Brookline, MA 02446
| Ordered by | Paddy Kalish, OD |
|---|---|
| Attempted by | |
| Report status | |
| Eyes attempted | |
| Test | Online letter contrast sensitivity screener (Pelli-Robson tradition) — Sloan letters at 40 cm, screen-calibrated |
How to read the score: log contrast sensitivity runs from 0 up to a ceiling of about 2.20 on this test — higher is better. 1.65 or higher is within the normal range for a screening; 1.35–1.64 is reduced and worth checking in the office; below 1.35 is markedly reduced.
Your report was prepared automatically when the test ended — there is nothing to approve or send. Download another copy as a PDF below if you would like one for your own records.
Screening only — not a diagnosis and not a prescription. A home screen's brightness, glare, and grey steps limit precision, and the very lowest contrasts are coarse on ordinary displays, so a reduced score here can reflect the screen as well as the eye. The clinic's printed contrast chart remains the definitive measure, and any reduced result should be confirmed in the office.